Physical and Chemical Changes. What is the difference between physical and chemical properties?

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Presentation on theme: "Physical and Chemical Changes. What is the difference between physical and chemical properties?"— Presentation transcript:

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Physical and Chemical Changes

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What is the difference between physical and chemical properties?

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Physical Change Although some extensive properties (like shape, phase, etc.) of the material change, the material itself is the same before and after the change. The change can be “undone.”

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Chemical Change The substances present at the beginning of the change are not present at the end; new substances are formed. The change cannot be “undone.” (Exception: Some reactions are reversible.)

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Physical or Chemical Change? How can you tell?

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Physical or Chemical Change? Rusty Nail How can you tell?

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Physical Changes Aluminum foil is cut in half. Clay is molded into a new shape. Butter melts on warm toast. Water evaporates from the surface of the ocean. A juice box in the freezer freezes. Rubbing alcohol evaporates on your hand.

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Chemical Changes Milk goes sour. Jewelry tarnishes. Bread becomes toast. Rust forms on a nail left outside. Gasoline is ignited. Hydrogen peroxide bubbles in a cut. Food scraps are turned into compost in a compost pile. A match is lit. You take an antacid to settle your stomach. Your body digests food. You fry an egg.